Variable renewable energy

Variable renewable energy (VRE) or intermittent renewable energy sources (IRES) are renewable energy sources that are not dispatchable (adjustable on demand) due to their fluctuating nature, such as wind power and solar power, as opposed to controllable renewable energy sources, such as dammed hydroelectricity or bioenergy, or relatively constant sources, such as geothermal power. The use of small amounts of intermittent power has little effect on grid operations.

Source: Wikipedia — Variable renewable energy (CC BY-SA 4.0)